1. Field of the Invention
The invention relates to fluid pumps, and is directed more particularly to a fluid pump and expandable energy storage device.
2. Description of the Prior Art
High impulse, short duration fluid pumps are known in the art and are used in submarine torpedo launch systems. Usually, such pump systems require high power piston or turbine machinery to provide the required high velocity fluid flow in a very short time. An attractive alternative to high-powered machines are relatively simple elastic bulbs which expand to contain a volume of fluid, such as sea water, under pressure. Upon release of the water, the bulb quickly returns to its non-expanded state, propelling the water at a high velocity into and through a torpedo tube to effect launch of a torpedo, or other missile, therein.
Fluid pumps and expandable energy storage devices are shown and described in U.S. Pat. No. 4,848,210, issued Jul. 18, 1989, in the name of Laurent C. Bissonnette, and U.S. Pat. No. 5,200,572, issued Apr. 6, 1993 in the name of Laurent C. Bissonnette et al.
In the '210 patent there is disclosed a bladder device for storing potential energy when distended and rapidly converting that stored energy into kinetic energy of a working fluid, for quietly ejecting a projectile from a launch system into a surrounding fluid medium. In the '572 patent there is disclosed an elastomeric impulse energy storage and transfer system including an accumulator body of elastomeric material, the body having an opening at a base portion thereof, and having in elevation an ellipsoidal configuration. The body receives and discharges fluid through the opening and is expandable and contractible in response to receiving and discharging, respectively, the fluid. The body retains the ellipsoidal configuration when in an expanded condition. A submarine projectile launch system includes the accumulator body as a component thereof.
An innate difficulty in structuring such pump and storage devices is in the provision of an elastomeric bulb or disc adapted to contain a large volume of relatively incompressible liquid at pressure sufficiently high to propel the liquid at a high velocity. The bulbs or discs typically are provided with thick elastomeric walls which undergo large strains in the accomodation of the requisite fluid volume. An elastomeric wall for such an application has demanded compromises in the selection of material for reliability, durability, strain energy capacity, fracture toughness, and chemical resistance. Further, such elastomeric bulbs require a relatively large volume of space, always at a premium in submarines.
Accordingly, there is a need for a fluid pump and expandable energy storage device which provides reliability and durability, which provides the required strain energy and which provides the required volume of fluid but with reduced strain levels in the elastomeric, energy-storing members.